324 The Diseases of Animals 



found to be most economical. The vats should be fifty 

 feet long and so arranged that the temperature can be 

 maintained by steam admitted at the bottom. 



The dipping of sheep should be repeated within ten 

 days ( preferably about a week ) , in order to destroy 

 mites which hatch after the first dipping. Dipping 

 sheep destroys not only the scab mite, but also sheep 

 ticks (page 338) and other parasites of the skin. Scabby 

 sheep should be carefully fed and cared for, and no 

 healthy sheep allowed in contact with them or on 

 ground that has been infested, until the disease has been 

 eradicated and the premises disinfected. 



Scab of Cattle 



Cattle scab or itch is caused by a mite (Psoroptes 

 communis,v8ir. bovis) very closely resembling the mite of 

 sheep scab. It occurs mostly in the great cattle -grow- 

 ing regions of the West, where it is known as Texas, 

 range, or cattle itch. 



Cattle itch does not cause apparent trouble during 

 the grazing season; but when the cattle are on dry feed 

 in winter, or when first turned on grass in early spring, 

 the trouble exhibits itself, and may cause considerable 

 loss. It is usually confined to young cattle, or to those 

 out of condition. The first symptom is an intense itch- 

 ing of the skin, usually in the region of the neck and 

 shoulders. The animals lick themselves, dig at the skin 

 with their teeth or horns, rub against posts and other 

 objects, sometimes even upon barbed wire, and often 

 tearing the skin until it bleeds. 



